Electrical sostenuto piano



Aug. 21, 1928. 1,681,635 l s. COOPER i ELECTRICAL SOSTENUTO PIANOOriginal Filed May 19. 1922 2 Sheets-Sheet l my. a

Aug, 21, 192s'.

S. COOPER ELECTRICAL sosTENUTo PIANO Original Filed May 19. 1922Patented Aug. 21, 1928.

UNITED STATES P TE'i rric ELECTRICAL SOSTENUTO PIANO.

Reled for application Serial No. 562,269, filed May 19, 1922. Thisapplication led January 18, 1923.

Serial No. 613,534.

This invention relates to a method and apparatus for initiating orsustaining the vibrations ot' a sonorous body, as for instance, a pianostring, in the production of the characteristic musical tone thereof.

The principal object of the invention is to provide for sustaining orinitiating the vibration of a piano string in the production ot itscharacteristic musical tone, with the least possible interference withsuch free and natural vibration ot' the string. l have previouslydevised and demonstrated an electrical sostenuto piano with certain ofthe electrical contacts located directly on the string and on thevibrating portion thereof, and to do away with mechanical interferencewith the free vibration ot' the string in making and breaking contact, Imade the contact member carried by the string, and the cooperatingcontact member, very light, and provided for the slightest possiblepressure between them. iVhile this arrangement has been satisfactory, Ihave, in the course ot experiments, found that other arrangements arefeasible and practical. In the present iiivention accordingly I haveaimed to control the energization of the electro-magnet which directlyati'ects the string by means of contact members entirely removed fromthe vibrating portion proper of the string.

Other objects and aims ot the invention, more or less broad than thosestated above, together with the advantages inherent, will be in partobvious and in part specifically referred to in the course of thefollowing description of the elements, combinations, arrangements otparts, and applications ot principles constituting the invention; andthe scope of protection contemplated will appear from the claims.

In the accompanying drawings, which are to be taken as a part of thisspecification, and in which I have shown merely a preferred form ofembodiment of the invention, Figure 1 is a partly diagrammatic showingof an arrangement of electro-magnet in connection with a string, soundboard, and other parts of a piano. including the application of one formof embodiment of my present invention; Figure 2 is an elevation showingpart of a piano structure with an embodiment of my invention appliedthereto; Fier. ure 3 is an elevation of a sound board or other resonatngmember of a piano structurewith a form of embodiment of my inventionapplied thereto; Figure 4 is a sectional view showing details ot'another form ot' embodiment of my invention; Figure 5 is an elevation ofthe subject-matter of Figure t1; Figure 6 is a view similar to Figure 4illustrating a modification; Figure 7 is ai sectional view illustratinganother form ot' embodiment; Figure 8 is an elevation at right angles tol igure 7; Figure S) is a View taken on the line 9 9 of Figure 7;Figures 10 and 11 show the circuit maker and breaker 2O and 3() more indetail. Referring to the numerals on the drawings, and particularly toFigure 1, there is shown at 1() a sounding board of a piano. 11 indiates a string, and 12 the bridge. 14; indicates the magnet placed inproximity to the string and included in a branch circuit 15, whichcircuit is normally open, but closed by the depression of piano key 16,which dcpression brings together contacts 17 and 1S, to close thecircuit so far as this normal break in concerned. erator is indicated at19, and in practice one battery will serve for a considerable number ot'magnets 14 and branch circuits 15. The circuit 15 also includes aresilient contact member 20, suitably iixed upon the sounding board 1t),or other resonating member constituting a part of or located inoperative proximity to the piano; and a co-operating contact memberwhich may be in the form ot' a carbon button for instance, indicated bvthe reference character 21. In Figure 1, I have shown tivo sets of thesecti-operating contact members 20 and 21, and it will be understood thateach one is in a branch circuit that ineludes an electro-magnet for aparticular string, controlled by a particular key 1G, though all ofthese circuits may be energized from the same battery 19 in a wellknownmanner. E

Assuming that the key lhas been depressed. resulting in the striking ofthe string 11 by hammer 22, the string 11 will be set in vibration.Causing characteristic vibration in the soundingr boaid 10. I have foundthat by locating the contact button 2l at some point on the soundingboard einpirically deteri'i'iined with reference. to the vibrations setup in the sounding board by the characteristic vibrations of aparticular string. theI 'contact 2 1 willvv be moved rel A battery orother genatively to the cooperating contact 2O with which it is normallyin contact at a momentwhen the portion of that string opposite itsmagnet is at a. particular point 1n the. path of movement of the string.This particular point in the path of movement of the string is such thatthe pulsation of current in the magnet, resulting from the cooperation between the vibrating contact 21 and t-he resilient contact 20 whichbearsagainst it, will energize th magnet to exert a pull on the string atamoment when the portion of the stringr opposite the magnet is movingtoward the latter. That is to say, the coopei ation of the' contacts tocause a pulsation of current in the magnet circuit is empirically fixedto occur at a definite moment which results, allowing for the time ittakes for the magnet to respond to the pulsation, in the magnet pullingupon the string when the string is moving toward the magnet. Thus thedesired true musical tone is obtained from the string, withoutinterfering at all with the amplitude of vibration or with the naturalmotion of the vibrating string, sincel none of the controlling contactsare carried by the string or in direct physical contact therewith.

I prefer that the resilient- Contact member 20 should bear againstcontact member 21 with a very light pressure, so. that as the soundingboard vibrates in response to the vibrations of the particular stringapproprinted to the particular button 21, the movements of the button 21as it travels with the vibrating sounding board will break or varycontact between the button and the Contact member 20 and consequently instep with the cnergizations of the magnet 14. llt will be evident thatthe amount of pressure exerted by the Contact member 20 may be variedand adjustable in accordance with conditions surrounding the particularstring, but the important thing is that every individual string in itsvibration will induce characteristic vibrations in the sounding board orother resonating member, and that by exploration such point may befound, where the contact member 21 is to be located for the securing ofthe desired tone in the string when the latter is vibrated. Instead ofranging over the sounding board and locating a desirable point for theContact member 21 appropriated to each individual string, I may placeupon the sounding,r boa-rd a collection of sets of contact members 2Oand 21, then a test is made for each individual string by connectingitwith iirst one and then another of these sets of contacts, until thatone is found which gives the desired tone results. And in Figure 3 thisidea is carried still further, by mount-ing a large number of sets ofcontacts 20 and 21 upon a supplemental sounding board 24, which will beattached or located. in proximity to the piano.

For each string one of the sets of contact members 20 and 21 will haveto be found by test as giving the desired tone results. It may be foundin practice that one set of contacts 2O and 21 Will answer for more thanone string.

In Figures 7., 8 and 9 the same idea is carried out, that is to say,there is a sounding board or auxiliary resonating member 10, whichcarries a plurality of resilient contact members 20, each of which isappropriated to a particular one or plurality of strings. These severalContact members 20, instead of engaging with individua-l cooperatingcontacts 21 as in the forms of the invention previously described, allengage with a common conductor or contact member 25, which is in theform of a. vibratile reed {irmly secured at one end to the sound board,preferably upon a block 26 secured to the sounding board. It will beobserved that each contact member 2O in Figures 7, and 9 engages at adiil'erent point on the Vibrating reed 25. `What these particular pointsare will be determined by experiment, that is to say, when a particularcontact. member 2O has been appropriated to a particular string, thatcontact member 2() Will be moved, bringing its contact end to bear upondifferent portions of the reed 25 until a point isfound where the stringgives satisfactory tone results upon energization of its magnet bydepression of its key 16. rilhe contact member 20 is then fixed intheposition vso discovered as by means of a. 10U screw 27. In thisembodiment also I have found that a single point in the reed 25, engagedby a single contact member may control more than one string. Thevibrations of the reed will be in synchronism 105 with those of thesounding board or other resonating member to which the reed is attached.

Referring to Figures 4, 5 and 6, 10 indicates the sounding board asbefore, and 12 110 the bridge. rIhe anchorage of the string is indicatedat 28. As is Well known, that part of the length of the string betweenthe bridge 12 and the anchorage 28 is not concerned in the production ofthe tone of the 115 string, that is to say, its vibrations arenegligible so far as tone production is concerned. However, there is acertain amount of vibration in this short length of the string betweenthe bridge and the anchorage, and 120 this vibration is necessarilysynchronous with the vibrations of the main length of the string.Accordingly, in Figures 4 and 5 I show a contact member in the form of awire 29 fastened to the bridge 12, in proX- 125 imity to and in contactwith the string 11. Of course this wire 29 may be fastened to the stringitself at the point Where the latter bears on the bridge. Thecooperating contact member may be a coiled spring 3() 130 string.

supported by aplate or bar 31 of non-conducting material rigidlyIfastened to the piano frame at a propel' distance from the string 11.The wire 29 extends down vinside the coil 30, and the end of the wire 291s caused to bear against the inner circumference of the coil at suchpoint around said circumference as will bring aboutl the truesynchronism between the energization of the magnet and the phase ofvibration of the Of-course both the wire on the bridge andthe coil 30will be in circuit with a magnet, the same as contacts 2O and 21described with reference to Figure 1 and rthe general operation issubstantially the saine as that already described With reference toFigure 1. u

In Figure 6 there is 'shown a modification, to the extent that thecontact wire 29 instead of being fixed in position 1s adjustablelengthwise of the portion of the string 11 between bridge andanchoragexby means of a sleeve or loop attaching portion 32 embracingthe string, and held in fixed relation thereto by means of a clip or setscrew or soldering or otherwise. By moving the wire 29 up and down onthe stringa point may be found where the greatest musical value of thestring 11 is obtained. This adjustment may be made in addition lto theadjustment of the point of contact of the end of the wire 29 with theinner circumference of the coil 30, as previously described.

It will be evident that in all the forms of the invention described-thefull and free vibration of the piano string is not interfered with atall, while at the same time provision is made for securing the best tonevalues from the strings by proper co-ordination of the energization ofthe magnet with the vibration of the string.

In all forms of the invention herein described the piano string sets upcharacteristic vibrations in ay sounding board or other vi- -bratilemember which is preferably associated with the piano but no directlyassociated with t-he vibrating sound-producing portion of the string. Amagnet is provided, whose energization results in a pull upon thestring. The vibrations induced by the string at an empiricallydetermined point on the vibrating member are caused to control thepulsations of current in the magnet circuit, and this point is such aone that the pulsation energizes the magnet to cause a pull upon thestring when the string is moving towards the magnet.

This application is filed as a substitute for my application Serial No.562,269, filed May 19, 1922.

I claim:

1. The herein described method of vibrating the strings of a. musicalinstrument which comprises producing pulsations of current m magnets forvibrating the respective strings and locating circuit controllers forthe respective magnets on vibratile portions of the instrument atempirically predetermined points which vibrate in a definite timerelation with the strings which are actuated by the respective magnets,and in accordance with such empirical determinations locatingdif'l'erent magnets for coaction with different strings in such mannerthat a controller havingY a vibration-location causing its magnet tohave a more advantageous coaction with one string than another, willhave its magnet. arranged to coact with the first of the twolast-mentioned strings.

2. The herein described method of vibrating the strings of a musicalinstrument which comprises producing pulsations of current in magnetsfor vibrating the respective strings and locating circuit controllersfor the respective magnets on the sounding -board of the instrument andat empirically predetermined points thereon which naturally vibrate in adefinite time relation with those strings which are actuated by therespective magnets, and in accordance with such empirical determinationslocating different magnets for coaction with ditl'erent Vstrings in suchmanner that a controller having a vibration-hication causing its magnetto have a more advantageous coaction with one string than another, willhave its magnet arranged to coact with the first of the tWolast-mentioned strings.

3. The herein described method of vibrating the strings of a musicalinstrument which comprises producing pulsations of eurent iii magnetsfor vibrating the respective strings, determining by exploration thosepoints on vibratile portions of the instrument which differentiallyvibrate in such manner that one point has a more favorably timedvibration with one particular string than another, and locating circuitcontrollers for the magnets of the respective strings on the criticalpoints ascertained in accordance with such favorable vibration-relationcharacteristics.

4. The method of operating a sostenuto piano which comprises locatingcircuit controllers on the sound board of the instrument at empiricallypredetermined points thereon which differentially vibrate in such mannerthat one point has a more favorable timed vibration with one particularstring than another, and controlling the magnets for the respectivestrings from the circuit controllers, said controllers being located sothat magnets for different strings are controlled by controllers atpoints having such favorable vibration-relations with said strings.

5. The method of operating a sostenuto piano which comprises locating acircuif controller on a vibratile portion of the piano at that one oftwo possible points which vibrates in the more favorable time relationwith a particular string andcontro1ling a magnet for vibrating thatstring by said thus-located circuit controller.

6. The method of operating a sostenuto piano which comprises determiningempirically upon that one of several vibratile portions of theinstrument which vibrates naturally in the more favorable time relationwith a given string and fixing a circuit controller for the actuatingmagnet of that particular string at such point.

7. The method of operating a sostenuto piano which comprises locatingthat one of a plurality of portions of the sound board of the instrumentwhich vibrates naturally in the more favorable time relation with aparticular string and controlling the actuating magnet for that stringby a circuit controller mounted on that portion of the sound board.

8. The method of operating an electromagnetic sostenuto device for apiano string which consists in causing a pulsation of current in amagnet for vibrating the string at a moment of time such that theconsequent energization of the magnet will occur when the string ismoving towards the magnet and timing the initiation or such pulsation bythe vibration of a selected one of two points on a sounding boardassociated with the string, such selected point being that one havingnaturally a more favorably timed vibration,`

than the other point, relative to the vibration of said string.

9. The method of operating an electromagnetic sostenuto device for apiano string which consists in causing a pulsation of current in amagnet for vibrating the string at a moment of time such that theconsequent energization of the magnet will occur when the string ismoving towards the magnet and controlling the initiation of suchpulsation by the vibration of a vibratile member of the piano other thansaid string, by loeating a control for the magnet circuit upon, andmaking it subject to the vibrations of, a particular one of two pointson said vibratile member, empirically determined as the vibrations ofsaid element are more favorably timed with those of the string.

11. In a plano, the combination with the sound-producing strings and anelement vibrated thereby, of electro-magnetic means for vibrating astring, including a circuit and cooperating contacts therein, one Iofsaid contacts being carried and controlled by said vibrating element ofthe piano, the latter contact being at that one of two points on saidvibrating element whereat the natural vibration of said element is morefavorably timed with the vibration of said string.

l2. In a piano, the combination with the piano strings and the soundboard associated therewith, of magnets for vibrating the dif ferentstrings and circuit controllers for the several magnets each located ona particular portion of the sound board which vibrates naturally in adefinite time relation with the string actuated by the magnet itcontrols, each of the two points selected :tor the controller having, ascompared with the other, a more favorable vibration-relation with itsassigned string.

13. In a piano, the combination with vthe piano strings and a membervibrated thereby, of magnets for vibrating the different strings andcircuit controllers for the several magnets located at points on saidvibrating member which vibrate in a definite time relation with thestrings actuated by the respective magnets which they control, each ofthe two points selected for the controller having, as compared with theother, a more favorable vibration-relation with its assigned string. lsi In testimony whereof I aiiix my signature.

l SIMN CGGPER.

